1. Technical Field
This invention relates to a hybrid vehicle.
2. Background Art
From the standpoint of an improvement in fuel efficiency, a hybrid vehicle using a combination of an engine (internal combustion engine) and a motor (electric motor) is proposed (see JP-A No. 2008-080986 (FIG. 3), for example).
As shown in FIG. 3 of JP-A No. 2008-080986, a power unit (18) (a parenthesized number indicates a reference sign described in JP-A No. 2008-080986, the same shall apply hereinafter) includes a hybrid engine including a motor/generator (36) in addition to an internal combustion engine (26) in which an air-fuel mixture is ignited by an ignition plug (54) to cause an explosion in a combustion chamber (26a).
A transmission (42) is provided in a lower portion of the internal combustion engine (26). For shifting gears, a shift drum (112) in the transmission (42) is rotated. The shift drum (112) is rotated by a shift pedal depressed by a rider (JP-A No. 2008-080986, paragraph 0039, line 1).
A vehicle (particularly, a motorcycle) in which a rider operates the shift pedal to mechanically operate a transmission (42) through the link therebetween is widely available.
Also, a system is proposed in response to automation requirement in recent years, in which information on operation of a transmission operating element is converted into an electric signal without mechanical coupling between the transmission operating element and a transmission so that an actuator is controlled based on the electric signal and thus the actuator rotates the transmission. In this system, since the actuator rotates the transmission, a force required for the rotation can be freely set, increasing design flexibility.
On the other hand, the actuator is mounted, for example, in a crankcase. However, since the crankcase does not have sufficiently much inner space, the major portion of the actuator protrudes outside the crankcase. In the hybrid engine, an increase in size of the engine is expected due to the overhang of the actuator in addition to the overhang of the motor. If the amount of overhang is to be decreased, the range of design flexibility will be almost always narrowed. As a result, a decrease in design flexibility is expected.
To avoid this, a hybrid vehicle needs preferable layout to provide an actuator in a transmission mechanism.